Ghosty HtmlAgilityPack | 易学教程

问题

I have got really ghosty effect here. I try to replace an img node. and if I print out the document html once, nothing will happen. If I don't print out the document html, the img tag can be successfully replaced. It's really strange, can anyone explain?

my html code

<!DOCTYPE html>

<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="utf-8" />
    <title></title>
</head>
<body>
    <div id="swap"></div>
</body>
</html>

and my c# code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using HtmlAgilityPack;
using System.IO;
namespace htmlagile
{
    class Program
    {
        static void Main(string[] args)
        {
            HtmlDocument htmldoc = new HtmlDocument();
            string htmlstring;
            using (StreamReader sr = new StreamReader("HTMLPage1.html"))
            {
                htmlstring = sr.ReadToEnd();
            }
            htmldoc.LoadHtml(htmlstring);
            var div = htmldoc.DocumentNode.SelectNodes("//div");

            Console.WriteLine(htmldoc.DocumentNode.OuterHtml);

            foreach (var item in div)
            {
                HtmlNode newTag = htmldoc.CreateElement("p");
                newTag.SetAttributeValue("id", "change");
                item.ParentNode.ReplaceChild(newTag, item);
            }
            Console.WriteLine(htmldoc.DocumentNode.OuterHtml);
        }
    }
}

if I comment out my first console.WriteLine, the element can be successfully changed.

回答1:

It's a bug in the agility pack. They cache the OuterHtml and InnerHtml values. When a change happens, they only invalidate the immediate parent. Because you are printing the root, it still has the old cached value.

http://htmlagilitypack.codeplex.com/workitem/30053

If you change to printing out the parent div, you should see that the changes actually were performed:

Console.WriteLine(div.OuterHtml);

来源：https://stackoverflow.com/questions/15989191/ghosty-htmlagilitypack

标签

html-agility-pack